I answered a question this morning about how to get the number of rows returned from a mysql query in PHP. Relatively easy question, so I wasn't amazed when Paolo Bergantino left a comment that he was working on getting his answer in when I got mine in. Fair game.

From the front page of SO, the question was advertised as having 2 answers, the second from Adam Plumb. But when you go into the question...there's only my answer. When you go to Adam's profile, his recent tab doesn't show that he answered this question. The front page, however, still says he answered the question.

I'm assuming he answered it, but saw that I had already given the same answer. When this happened, he deleted his answer and up-voted mine, likely. Should the front page still contain his answer with the question?

1 Answer
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I expect the front page was a caching issue. For performance reasons many of the numbers you see (vote counts / etc against posts; article counts against tags; etc) are heavily cached and re-used - so may be a minute or so out of date.

I thought cache may have been the culprit too.
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Jonathan SampsonJul 9 '09 at 11:50

To be technical, it's actually a side effect of database de-normalization. The latest activity time and user are stored in the post row, and it would be somewhat expensive to recreate this data every time a deletion happened.
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Kyle CroninJul 9 '09 at 13:55